1. Field of the Invention
The method relates to a method for removing and drawing a synthetic thread to form a fully drawn yarn (FDY) as well as a device for performing the method.
2. Description of Related Art
For the manufacture of synthetic threads especially for textile applications it is generally known that the multifilament threads are drawn to a lesser or greater extent after the melt spinning process, depending on the yarn types to be manufactured. Depending on the degree of drawing, we distinguish between so-called POY yarns or FDY yarns. POYs (pre-oriented yarns) have a pre-oriented, not yet completely drawn structure and are normally further processed into the finished yarn during a second process step, such as false turn texturizing. In contrast, FDYs (fully drawn yarns) are fully drawn and can be used directly for the subsequent processing of a large-size textile product.
The synthetic threads are drawn by means of driven guide jackets of several galettes, wherein the threads are guided with contact along the circumference of the guide jackets. The guide jackets of the galettes are at least partly heated to heat the threads for drawing or relaxing. Because strong drawing analogously requires high differential speeds between the guide jackets and the galettes on the one hand and the threads are heated by way of contact with the heated guide jackets on the other hand, long contact lengths between the thread and guide jacket are required to heat the threads with high speeds. For this reason, a galette pair is normally used for removing and drawing synthetic threads to form fully drawn yarns, said galettes having two guide jackets driven with identical circumferential speeds and guiding the thread with several loops. Said method and said device have been disclosed for example in DE 199 58 245 A1.
With respect to the disclosed method and the disclosed device, each of the galette pairs comprises two driven guide jackets, on which the thread is guided with a plurality of loops. In this respect the guide jackets of a galette pair interact in order to carry out the thermal treatment on the thread and to pull the thread out of a spinning zone or to draw it in a drawing zone. The number of loops on the guide jackets is selected in such a way according to the ratio of speeds that the desired drawing temperature is reached when the thread has run off of the guide jacket. However, any contact between the thread and a guide surface generally generates friction effects which may result in irregularities of the individual filaments due to the multifilament structure of the thread.
A method and a device for removing and drawing a multifilament thread has been disclosed in DE 31 46 054 A1, in which the thread is guided along the guide jacket of a galette with a single loop for removing the thread. However, the guide jacket is not heated and therefore, the thread is drawn cold in the subsequent zone. However, said cold drawn threads generally have the disadvantage that extremely high drawing forces need to be generated, resulting in considerable problems especially in connection with the manufacture of a plurality of simultaneously guided threads. Another disadvantage of the method is that the consistently slip-free transmission of the drawing forces is extremely difficult with a single loop on the guide jacket of the galette.
However, methods and devices have generally been disclosed in the prior art in which the thread is heated contactless by means of a radiant panel. For example, a method and a device for removing and drawing a multifilament thread are described in WO 2007/115703 A1 in which the thread is guided on the guide jackets of the galettes with a single loop. In the process, free treatment zones used to heat the thread with radiant panels are formed between the guide jackets. Consequently, said methods and devices require longer free guide pathways of the thread to allow adequate temperature equalization with high speeds.